European Government Group Says Radar Satellites and Wi-Fi Cannot Coexist
BRUSSELS — The intergovernmental organization that coordinates European radio-frequency allocations has concluded that Wi-Fi devices cannot peacefully coexist with satellite radars in the same slice of radio spectrum, the head of the body’s technical committee said Jan. 28.
The opinion of the the 48-nation European Conference of Postal and Telecommunications Administrations (CEPT) places an ostensibly disinterested arbiter squarely in the camp of radar Earth observation systems fighting a proposed incursion into their reserved spectrum by terrestrial broadband companies.
“This was a delicate issue,” said Eric Fournier, chairman of CEPT’s Electronic Communications Committee, noting that European Union policy generally favors the extension of terrestrial broadband spectrum use. “But we have concluded that [spectrum] sharing between WiFi and radar Earth observation satellites will not work.
“To prevent interference the Radio LANS [wireless broadband devices] would need to operate at 10 times lower power levels than they are using in adjacent bands. There is no possibility of sharing, and no reliable data has been put on the table suggesting otherwise,” Fournier said.
Several large backers of terrestrial broadband, including Cisco Systems, Intel, Qualcomm and Broadcom, in early January presented to CEPT a study saying that sharing was possible without perturbing the satellite radar signal.
The 20-nation European Space Agency concluded otherwise and presented a different set of results to CEPT.
At stake is not only Europe’s Sentinel 1 radar satellite system, but also Canada’s Radarsat Constellation Mission, now in development. Both are designed to send signals in the 5-gigahertz region of radio spectrum that has been set aside for such use.
While radar Earth observation systems have priority access to the spectrum, other users are welcome to use the same frequencies once they demonstrate that sharing is feasible without causing undue trouble for the incumbent users.
Because the CEPT is generally viewed as having no axe to grind in the debate — it is no more beholden to radar satellite backers than it is to terrestrial wireless networks — its view could prevent a full-scale conflict at the next World Radiocommunication Conference (WRC), scheduled for 2015. These conferences, held every four years, make the final decisions about wireless frequency use and satellite slots.
In the run-up to the meetings, regional groupings like CEPT attempt to settle issues to be discussed at WRC.
The radar satellites’ owners said that, because these systems’ signals are sent from several hundred kilometers in altitude in low Earth orbit, their strength is depleted when they hit the ground, making them that much more vulnerable to Wi-Fi networks.
It remains to be seen whether the U.S. delegation to WRC, whose technical input is provided by, among others, the National Telecommunications and Information Administration (NTIA), will come to the same conclusion as CEPT.
Fournier’s remarks, made during a two-day space policy conference here at the European Commission, were welcomed by Earth observation system promoters, including the Commission, which owns the Sentinel 1 satellite series. The first Sentinel 1 is scheduled for launch this spring.
In a related development, CEPT appears on the verge of reducing protections afforded to satellite communications in the upper portion of the 3- and 4-gigahertz frequency band.
Fournier said that, in Europe, the upper portion of this band, between 3,800 and 4,200 megahertz, is used for large Earth station antennas that can be protected even if terrestrial wireless systems are active in the same radio bands.
Outside Europe, Fournier said, is a different story, and many nations, notably in Africa, still use C-band and have not moved to Ku-band as has much of Europe and North America. Because of this, he said, CEPT will not urge a global move to permit terrestrial wireless devices into the now-protected satellite C-band spectrum.
Romain Bausch, chief executive of satellite fleet operatorof Luxembourg, who spoke at the conference on behalf of the European Satellite Operators Association, said many satellites that cover Europe in C-band also have coverage of the Middle East and Africa.
Fournier said these antennas in Europe could be protected and that the demand for wireless broadband — 4G mobile now, 5G mobile is next — is growing so quickly that difficult tradeoffs need to be made for the use of the limited resource that is radio frequency.
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